sim_mass_with_ramp_force_input.m

function xdot = sim_mass_with_ramp_force_input(t, q, M, Fs, Fc, sigma_0, sigma_1, sigma_2, vs, force_rate)   
    u = force_rate*t;     % ramped-up force input  
   
    zdot = q(2) - ( (q(3)*abs(q(2))*sigma_0) / (Fc+(Fs-Fc)*exp(-(q(2)/vs)^2)) );
    F = sigma_0*q(3) + sigma_1 * zdot + sigma_2*q(2);

    qdot_1 = q(2);
    qdot_2 = (u - F) / M;
    qdot_3 = zdot;
    xdot = [qdot_1 ; qdot_2; qdot_3 ];
end